The Mutant Mouse Regional Resource Center (MMRRC) at the University of Missouri (MU) provides a unique repository service by importing, storing and distributing a vast number of mutant mouse strains, embryonic stem cells and related reagents as well as performing research to continuously improve the Resource Center. Genetically-engineered mice (GEM, i.e., transgenics, knock-outs and knock-ins) are invaluable to almost all fields of medicine. Tens of thousands of GEM have been created over the last two decades to facilitate better understanding of developmental biology and disease and to test and improve the function of drugs and therapeutics. Since the MMRRC Network began in 1999/2000, it has evolved into a major resource for the research community with capabilities and a combined inventory of mouse lines and embryonic stem (ES) cells that exceeds the capacity of other mouse repositories worldwide. The overall goal of this proposal is to continue the services and expand the functions and capabilities of the MU MMRRC. The specific aims are to 1) provide biomedical investigators with the mouse models and related reagents they require for their research, 2) provide value-added services to aid the biomedical research community, and 3) perform research that has broad application to all models distributed. Over the next five years, the MU MMRRC will continue to rederive imported mice to a pathogen-free state; cryopreserve gametes and embryos; perform genetic and infectious disease monitoring to ensure quality; and distribute live mice, cryopreserved germplasm, or tissues. Research efforts will develop more economical and efficient means of cryopreservation/cryoresuscitation and will characterize intestinal microbiota to ensure reproducibility of results from studies that use distributed models. The MU MMRRC will also continue to transition to a self-sustaining unit by offering services to generate program income. Services include cryopreservation, cryoresuscitation from embryos or sperm, rederivation, genotyping and assay development, marker-assisted genetic analysis for development of speed congenics, karyotyping, colony management, phenotyping, and microbiome analysis.